The crossing is due to revert to public ownership in 2018 but transport minister Stephen Hammond recently played down the chances of the tolls being slashed or the Welsh Government gaining control.

He said the UK Government had “several hundred million pounds” of debt that needed to be repaid and this would not happen until the early 2020s.

The AA, on Wednesday, raised the prospect of the crossing being sold. It noted that in 2009 the Labour Government had listed the Dartford Crossing among £16bn of public assets it was prepared to sell.

Paul Watters, the AA’s head of road policy, said: “It may well be on the balance sheet fairly soon for the Government as an item worth disposing of.”

Mr Watters said he was wary of the tolls being used to fund other improvements, fearing it would allow other spending on roads to be reduced.

Iestyn Davies, of the Federation of Small Businesses in Wales, had similar concerns.

He said: “Whilst we recognise the need to maintain what is clearly a key link in Wales’ transport and economic infrastructure, the tolls should be sufficient to maintain the running of the bridge and not simply used as a revenue stream.

“We see it as unwise to assume that future tolls could be used as an income stream to fund other projects; the case for any major infrastructure projects or improvements should be made on their own merit.”

Speaking after the toll increase was announced, the First Minister stressed that the Welsh Government wanted to see a reduction in the charge for using the crossing.

He said: “We couldn’t abolish the tolls, let’s be perfectly frank about that. But of course any money that is raised could be applied to the M4 in Wales.

“As to what the toll should be, that is something we would have to look at. We could look to reduce the tolls.”

The Westminster Welsh Affairs committee has suggested a £1.50 toll could cover the maintenance costs but Mr Jones would not be drawn on the amount motorists could face.

He said: “The important point is of course that still leaves scope for having that extra money which we could spend on the M4 in Wales.”

Emma Watkins, director of CBI Wales, said: “[We] would support what the First Minister has said in terms of using the money from tolls to fund infrastructure, especially for improvements to the M4. That’s a key issue for businesses in Wales and we know the money won’t just come out of the air.

“If the tolls can be used to fund investment to the M4, such as the M4 relief road, that is something we’d support.

“We’d probably expect to see some reduction in the level of tolls, particularly for domestic users and freight. If the Welsh Government had control, they could look at giving people a sort of toll holidays – perhaps as an incentive to use Cardiff Airport, you might have the Severn Bridge toll free if you come from England.”

The FSB’s Mr Davies warned the present situation was damaging the economy, saying: “Unremitting rises to the Severn tolls add insult to injury in terms of further weakening the competitiveness of the Welsh business community.”

The AA’s Mr Watters favoured amassing a maintenance fund that would allow the toll to be scrapped.

He said: “If there was a way of getting the fund in place and removing the tolls altogether, I think drivers might vote for that.”

The cost for vans and minibuses travelling west will rise from £12.10 to £12.40 (+2.5%), and from £18.10 to £18.60 (+2.8%) for lorries and coaches.

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